It is generally known that obesity is a common condition and a major public health problem in developed nations, including the United States of America. Today, 64.5% of American adults, about 127 million people, are either overweight or obese. Data demonstrated 300,000 Americans die prematurely from obesity related complications each year. More than 25% of children today are overweight or obese in the United States of America, hence the number of overweight Americans has increased steadily and will continue to increase in the coming years. Obesity costs the United States an estimated $100 billion annually in direct and indirect health care expenses and in lost productivity. This trend is also apparent in many other developed countries.
Morbid obesity is defined as more than 100 pounds greater than normal body weight or a body mass index (BMI), greater than 40 kg/m2 and is present in 5% of the U.S. population. A BMI greater than 30 kg/m2 is associated with significant co-morbidities. Morbid obesity is associated with many diseases and disorders, including diabetes, hypertension, heart attacks, strokes, dyslipidemia, sleep apnea, Pickwickian Syndrome, asthma, lower back and disc disease, weight-bearing osteo-arthritis of the hips, knees, ankles and feet, thrombophlebitis and pulmonary emboli, intertriginous dermatitis, urinary stress incontinence, gastro esophageal reflux disease (GERD), gall stones, and sclerosis and carcinoma of the liver. In women, infertility, cancer of the uterus and cancer of the breast are also associated with morbid obesity. Taken together, the diseases associated with morbid obesity markedly reduce the odds of attaining an average lifespan and raise annual mortality in affected people by a factor of 10 or more.
Current treatments for obesity include diet, exercise, behavioral treatments, medications, surgery (open and laproscopic) and endoscopic devices. There are currently three (3) weight loss drugs approved by the U.S. Food and Drug Administration. Orlistat (XENICAL®) provided by Roche is a non-systemic inhibitor of the enzyme lipase that works by interrupting the action of lipase in breaking down fats. Sibutramine hydrochloride (MERIDA®) is a non-amphetamine appetite suppressant that inhibits brain chemicals involved in appetite, thereby promoting a signal of satiety. Phentermine (ADIPEX-P®) is a structural analog of amphetamine and is also an appetite suppressant indicated for exogenous obesity.
In addition, there are currently a number of clinical trials on-going for treatments of obesity. One line of enquiry is based around the chemistry of the hormone called Human Amylin, which plays a role in the regulation of appetite and food intake. Mid-stage clinical trial results with one of these products have shown a weight loss of 3.5 kg (7.7 lbs) over 60 weeks. While these drugs have shown signs of greater efficacy, there has not been developed any high efficacy pharmaceutical treatment. Further, the issue of short-term and long-term side effects is always of concern to consumers, pharmaceutical providers and their insurers.
Laporoscopic bariatric surgical procedures in current use include Laporoscopic V or vertical gastroplasty, laporoscopic gastric bypass with Roux Y Limb and a Laporoscopic Placement of Lap Band. These procedures have been reported to result in marked lasting weight reduction in the majority of morbidly obese patients when assessed five years after operation. Studies of the health-related quality of life outcomes of these procedures have documented sustained significant improvements in all parameters measured. Diet or drug therapy programs have been consistency disappointing and fail to bring about significant, sustained weight loss in the majority of morbidly obese people.
Currently, most (95%) morbid obesity operations are, or include, gastric restrictive procedures, involving the creation of a small (15-35 ml) upper gastric pouch that drains through a small outlet (0.75-1.2 cm), setting in motion the body's satiety mechanism. About 15% of morbid obesity operations done in the United States involve gastric restrictive surgery combined with a malabsorptive procedure. This divides small intestinal flow into a biliary-pancreatic conduit and a food conduit. Potential long-term problems with surgical procedures are notorious and include not only those seen after any abdominal procedure, such as ventral hernia and small bowel obstruction, but also those specific to bariatric procedures such as gastric outlet obstruction, marginal ulceration, protein malnutrition and vitamin deficiency.
Additionally, there are in development multiple endoscopic procedures for obesity. Endoscopically placed gastric balloons restrict the gastric volume and result in satiety with smaller meals. Endoscopic procedures and devices to produce gastric pouch and gastrojejunal anastomosis to replicate laporoscopic procedures are also in development. These procedures, however, are not without their risks.
Gastric electric stimulation (GES) is another procedure that is currently in clinical trial. Gastric Electrical Stimulation (GES) employs an implantable, pacemaker-like device to deliver low-level electrical stimulation to the stomach.
The procedure involves the surgeon suturing electrical leads to the outer lining of the stomach wall. The leads are then connected to the device, which is implanted just under the skin in the abdomen. Using an external programmer that communicates with the device, the surgeon establishes the level of electrical stimulation appropriate for the patient.
While the exact way in which GES causes weight loss is not fully understood, it is believed that through low-level electrical pulses the therapy slows the intrinsic electrical waves in the stomach. Animal studies have shown that this electrical stimulation causes the stomach to relax, resulting in distension of the stomach. This distension triggers nerves in the stomach involved in digestion to send signals via the central nervous system to the brain that the stomach is “full”.
GES may also result in a decrease in gastrointestinal hormones such as CCK, somatostatin GLP-1 and leptin, all of which are associated with hunger. Recent work on GES has shown promising results in obese patients. GES results in 35% EWL (excess weight loss) beyond 24 months and the results are sustained and replicated. This technology is currently available in Europe and Canada and undergoing trials for FDA approval in the U.S
U.S. Pat. No. 6,901,295 to the present applicant describes a method and apparatus for electrical stimulation of the lower esophageal sphincter (LES). The device and method are directed toward inducing contraction of the LES to thereby combat gastro esophageal reflux disease (GERD). The claimed invention is directed towards using, amongst other things, sensing electrodes in the esophagus for detecting esophageal peristalsis so as to inhibit the electrical stimulation of the lower esophageal sphincter in order to pass food to the stomach. The disclosed device and method, therefore, increases LES tone after passage of food to the stomach. It is designed to prevent gastric reflux of acid material.
Published US Patent Application No 2005/0065571 to Imran discloses a responsive gastric stimulator which senses one or more parameters and then affects smooth muscle contractions and nerves associated with the stomach and/or biochemistry or secretions of the stomach. Stimulation may be directed to cause gastric retention of food for a greater duration by interfering with peristaltic contractions and/or the innate electrical potentials of the stomach.
Published US Patent Application No 2005/0090873 to Imran discloses a fixation device for holding stimulating electrodes in electrical contact with the wall of a portion of the gastrointestinal tract. This device comprises an expandable member that fixes electrodes in electrical contact with the gastrointestinal tract. The disclosure also extends to a method for treating obesity by controlling the pylorus to retain food in the stomach for a desired period of time to provide a sensation of satiety and/or to reduce hunger. The disclosed invention is relatively cumbersome and involves the intra-luminal insertion of an expandable member that presents some degree of risk in the duodenum. Food must be able to pass through the device while at the same time its expansive pressure must be sufficient to hold electrodes in place, but not damage the wall of the small intestine. The method and device also seek to control contraction of the pylorus by electrical stimulation of the duodenum.
Published US Patent Application No 2003/0144708 to Starkebaum relates to a method and system for treating patients with eating disorders, including obesity, through the delivery of electrical stimulation directly or indirectly to the pylorus of a patient to close the pyloric lumen to inhibit emptying of the stomach.
Published US Patent Application No 2004/0015201 to Greenstein discloses a process for electro-stimulation treatment of obesity. This disclosure is directed to electro-stimulation of the stomach, the lower esophageal sphincter, the pyloric sphincter and the ileo-caecal sphincter.
International Publication No WO2005/051486 to University Technologies International Inc. discloses a method and apparatus for gastrointestinal motility control. This discloses a complex multi-channel implantable device using one or multiple micro-system controlled channels and circumferentially arranged sets of two more electrodes to provide externally-invoked synchronized electrical signals to the smooth muscles via the neural pathways. The applicant describes invoking peristalsis but also corrupting peristalsis by implanting electrodes in the pyloric region or other areas of the stomach. The claimed invention relates to electrically-stimulating patches in the vicinity of an organ until the organ relaxes and applying electrical energy to the gastrointestinal tract to invoke a desired motility result. The identified specification does not disclose any means of feedback.
U.S. Pat. No. 6,611,715 to Boveja describes an apparatus and method for treating obesity and compulsive eating disorders using an implantable lever receiver and an external stimulator. The lead-receiver is in electrical contact with the left vagus nerve. The device is used for neuromodulating the vagus nerve with a result of appetite suppression.